Apparatus for the continuous extrusion of metals



July 6, 1 937. H HILL ET 2,085,977

APPARATUS FOR THE CONTINUOUS EXTRUSION OF METALS Filed July 29, 1936 '5A v A 21 L 20 24 1k 4 23 l 2 I4 23 Patented July 6, 1937 i'i'E starAPPARATUS FQR THE CGNTINUOUS EX- -TRUSION OF METALS a British companyApplication July 29, 1936, Serial No. 93,260 in Great Britain August 7,1935 4 Claims.

This invention deals with the extrusion of metal by a method dependentupon the relative rotation of two concentric members (usuallycyllndrical) into the space between which metal is fed and is theremoved forward in the plastic state by a. screwing action. The metal isusually fed in at one end of the two members while it is in the moltenstate and is then cooled so as to become plastic, s forced forward intoan extrusion chamber at the other end and there passes through a die orbetween a pair of dies. the two concentric members is provided with aseries of helical projections forming or equivalent to a screw threadand the other is also provided with projections which may run parallelwith the axis or may have some other form, being, for instance, screwthreads of the opposite hand to those on the first mentioned member.

The present invention applies to the type of machine in which the outerconcentric member is stationary and the inner rotates. In this type ofapparatus, it is usual to apply the drive to the rotary member at therear end. In accordance with the present invention, the drive is appliedat the front end. This may be the sole drive for the rotary member ormay be combined with a second drive applied at the rear end.

By applying the drive to the front end, the result is obtained that thedriving torque acts directly upon the rotary member at the place wherethe resistance to rotation is greatest. Owing to the fact that the metalnear the delivery end is at a lower temperature than that nearer therear end and is also at the maximum pressure, the metal near thedelivery end exerts the maximum frictional resistance and the maximumresistance to deformation or shearing.

The drive is applied at the front end by forming a lateral extension onthe driving member (that is, the inner member) or by attaching a drivingpart to the member. In either case, passages will be provided throughthe lateral extension or through the attached part for the passage ofthe metal from the driving member to the extrusion chamber and theoutlet at the die.

The invention will be further described by the aid of the accompanyingdrawing, which illustrates by way of example a form of construction of amachine in which the invention is embodied. Figure 1 is a longitudinalsection of the upper part of the front end (delivery end) of the ma.-chine. Figure 2 is an end view of the rotary member of the machinelooking from the plane A-A marked on Figure 1 in the direction of thearrows. Figure 3 is a developed section through One of a part of therotary member taken on the line B-B of Figure'2. In the parts with whichthe present invention is concerned the machine is symmetrical about thecentre line ill-4E9 Figure 1, so that it is unnecessary to show thelower half of the figure. The two concentric members are the outer partH, which also forms the casing of the machine, and the inner part itwhich at the front end has the laterally outward extending disc 53formed integrally with it. The adjacent surfaces of these two parts arecylindrical and work with slight clearance between them. In thecylindrical wall of the casing l i is out a helical thread M whichextends from the rear end, not

shown, to the front end in the neighbourhood of the disc 53. In thecylindrical face of the inner part i2 are cut a, number of longitudinalgrooves iii.

At the rear end of the machine, not shown, the space between the twoconcentric parts H and i2 is in connection with a.- feeding chamberwhich is kept full of molten metal, such as lead or lead alloy, so thatthe threads in the casing l l and the longitudinal grooves in the innerpart l2 are maintained full of metal. By the applica- 1 tion ofappropriate cooling means the metal within these spaces is renderedplastic, that is to say, it approaches near to the solid state. Therelative motion between the parts i2 and i I and the configuration ofthe adjacent surfaces of these parts causes the metal to be fed forwardtowards the delivery end by a screwing action. In this way it reachesthe extrusion chamber l6 and passes out between the dies H and i8. Inthe arrangement illustrated, the dies are circular so as to produce athin solid tube. This may, for instance, be the sheath of an electriccable, the core of which passes through the tube I9 so as to be drawnforward by the sheath extruded on to it between the dies. The tube I9 isfixed, being anchored by the rear part of the machine' The disc I3 isprovided on its periphery with a ring of teeth 20 through which it isdriven by a suitable pinion or worm. This disc, except at the part wherethe drive is applied, is enclosed between two fixed side walls 2| and22, which are bolted together near their outer periphery. The wall 2| isa continuation of the casing I I. The wall 22 forms the end plate of themachine and supports the outer die I8. The disc I3 is supported inposition by ball-thrust bearings 23 and by journal bearings 24.As-previously indicated, the part i 2 is also supported on the fixedcylinder l9. The adjacent surfaces of the parts l2 and I9 are preferablylubricated by oil under pressure TENT OFFICE and a similar system oflubrication may also be employed for the journal bearings 24.

To prevent the plastic metal from being forced out between the disc I3and the side walls 2i and 22, appropriate packing means are provided.These are shown as rings 25 which are housed in recesses in the adjacentfaces of the disc l3 and side walls 2| and 22. These packing ringscomprise an inner split ring of steel carrying a facing of softer metal,for instance copper, which works against faces on the two members(driving disc and stationary wall) and bridges the gap between them.These rings are pressed outward by the plastic metal behind them. Thesoft metal facing is deformed by pressure and rubbing so that it takesup a shape which fits the faces on the driving disc and side wall. Asimilar packing arrangement 26 is employed to prevent the entry ofplastic metal between the parts l2 and H3.

The ports 21 for the passage of the plastic metal through the disc 13 tothe extrusion chamber 16 can be shaped so as to cause a reduction of thepressure exerted by the plastic metal on the delivery side of the disc.This shaping can be carried out by taking account of the flowing motionand the high viscosity of the metal so that the streams passing throughand issuing from the ports will either flow clear of the surface of thedisc or exert a comparatively low backward pressure thereon, thatis, apressure materially less than would be the case if the forward motion ofthe metal were not taking place. This shaping is illustrated in Figures2 and 3. In these figures the numerals I and 8 have been used toindicate points on the walls of the ports. The arrow 28 indicates thedirection of rotation of the disc. The arrow 29 indicates the generaldirection of movement of the plastic metal in passing from one side ofthe disc is to the other. It will be seen that the stream of metalpassing through the central port shown in Figure 3, will press morestrongly against the surface 3-5 than against the surface 68. Thiseffect will tend to produce a resultant pressure in the direction of thearrow 29 which will in part balance the pressure in the oppositedirection which is exerted by the metal in the extrusion chamber IS onthe end surface of the rotating cylinder l2.

What we claim as our invention is:-

1. Apparatus for the continuous extrusion of metal by a screwing action,comprising two concentric members, receiving the metal between them andoperating thereon by their adjacent surfaces, the outer member beingstationary and the inner rotatable, an extrusion chamber at the deliveryend of the machine, said chamber having a shaped outlet for the metaland means for applying the drive for rotating the inner member at thefront (that is, the delivery) end thereof.

2. Apparatus for the continuous extrusion of metal by a screwing action,comprising two concentric members, receiving the metal between them andoperating thereon by their adjacent surfaces, the outer member beingstationary and the inner rotatable, an extrusion chamber at the deliveryend of the machine, said chamber having a shaped outlet for the metal, alaterally outward extending part on the inner member near the front endthereof, said part having a passage through it for the feeding of metalto the extrusion chamber, and rotary driving means operating upon saidpart.

3. Apparatus for the continuous extrusion of metal by a screwing action,comprising two concentric members, receiving the metal between them andoperating thereon by their adjacent surfaces, the outer member beingstationary and the inner rotatable, an extrusion chamber at the deliveryend of the machine, said chamber having a shaped outlet for the metal, adisc on the inner member near the front end thereof and extendingoutward therefrom, stationary side walls enclosing said disc andconnected with the outer concentric member, packing means between saiddisc and side walls and driving means acting on the periphery of saiddisc.

4. Apparatus for the continuous extrusion of metal by a screwing action,comprising two concentric members, receiving the metal between them andoperating thereon by their adjacent surfaces, the outer member beingstationary and the inner rotatable, an extrusion chamber at the deliveryend of the machine, said chamber having a shaped outlet for the metal, alaterally outward extending part on the inner member near the front endthereof, said part having a passage through it for the feeding of metalto the extrusion chamber, and rotary driving means operating upon saidpart, the walls of the passage through the said part being shaped anddisposed to reduce the end thrust exerted by the metal on the rotatablemember when it is rotating.

HARRY HILL. SYDNEY BECIQINSALE. WALTER FRENCH SLATER.

